Effect of a static magnetic field onEscherichia coliadhesion and orientation

2016 ◽  
Vol 62 (11) ◽  
pp. 944-952 ◽  
Author(s):  
Lotfi Mhamdi ◽  
Nejib Mhamdi ◽  
Naceur Mhamdi ◽  
Philippe Lejeune ◽  
Nicole Jaffrezic ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Bacterial Adhesion ◽  
Parallel Magnetic Field ◽  
Field Orientation ◽  
Static Magnetic Fields ◽  
Preliminary Study ◽  
The Difference ◽  
The Magnetic Field

This preliminary study focused on the effect of exposure to 0.5 T static magnetic fields on Escherichia coli adhesion and orientation. We investigated the difference in bacterial adhesion on the surface of glass and indium tin oxide-coated glass when exposed to a magnetic field either perpendicular or parallel to the adhesion surface (vectors of magnetic induction are perpendicular or parallel to the adhesion surface, respectively). Control cultures were simultaneously grown under identical conditions but without exposure to the magnetic field. We observed a decrease in cell adhesion after exposure to the magnetic field. Orientation of bacteria cells was affected after exposure to a parallel magnetic field. On the other hand, no effect on the orientation of bacteria cells was observed after exposure to a perpendicular magnetic field.

scholarly journals Magnetic Fields in AGN

1998 ◽  
Vol 164 ◽  
pp. 97-103 ◽  
Author(s):  
J. F. C. Wardle
Keyword(s):  
Magnetic Field ◽  
High Redshift ◽  
Parallel Magnetic Field ◽  
Field Orientation ◽  
Future Directions ◽  
Line Region ◽  
Rotation Measure ◽  
Narrow Line Region ◽  
First Time ◽  
The Magnetic Field

AbstractWe review VLBI polarization results. In particular, we discuss the a) “shock in jet paradigm”, b) the orientation of the magnetic field in jets as a function of optical identification, c) rotation measure and Faraday dispersion measurements as a probe of the narrow line region, and d) future directions of polarization observations. Results we emphasize are i) there is still a strong correlation between optical L/C ratio or EW and magnetic field orientation in the jets of blazars, even for high redshift weak-lined objects, ii) observed rotation measures are much smaller than expected from the properties of the NLR, except for some CSS sources. Also iii) a faint boundary layer or sheath (with a parallel magnetic field) has been observed around the jet of the weak-lined blazar 1055+018, and iv) circular polarization has been detected for the first time in the jets of 3C 84 and 3C 279.

scholarly journals First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Bin Zhou ◽  
Bingjun Cheng ◽  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Field Measurement ◽  
Vector Data ◽  
Magnetic Field Data ◽  
Night Side ◽  
The Difference ◽  
The Magnetic Field ◽  
Ground Calibration ◽  
Data Calibration

Abstract The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magnetometer (CDSM), and measures the magnetic field from DC to 15 Hz. The FGMs measure the vector components of the magnetic field; while the CDSM detects the magnitude of the magnetic field with higher accuracy, which can be used to calibrate the linear parameters of the FGM. In this paper, brief descriptions of measurement principles and performances of the HPM, ground, and in-orbit calibration results of the FGMs are presented, including the thermal drift and magnetic interferences from the satellite. The HPM in-orbit vector data calibration includes two steps: sensor non-linearity corrections based on on-ground calibration and fluxgate linear parameter calibration based on the CDSM measurements. The calibration results show a reasonably good stability of the linear parameters over time. The difference between the field magnitude calculated from the calibrated FGM components and the magnitude directly measured by the CDSM is just 0.5 nT (1σ) when the linear parameters are fitted separately for the day- and the night-side. Satellite disturbances have been analyzed including soft and hard remanence as well as magnetization of the magnetic torquer, radiation from the Tri-Band Beacon, and interferences from the rotation of the solar wing. A comparison shows consistency between the HPM and SWARM magnetic field data. Observation examples are introduced in the paper, which show that HPM data can be used to survey the global geomagnetic field and monitor the magnetic field disturbances in the ionosphere.

scholarly journals The effect of magnetic field on the dynamics of gas bubbles in water electrolysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yan-Hom Li ◽  
Yen-Ju Chen
Keyword(s):  
Magnetic Field ◽  
Swirling Flow ◽  
Gas Bubbles ◽  
Water Electrolysis ◽  
Platinum Electrodes ◽  
Optimal Layout ◽  
Parallel Magnetic Field ◽  
Hydrogen Bubbles ◽  
The Magnetic Field ◽  
Sluggish Flow

AbstractThis study determines the effect of the configuration of the magnetic field on the movement of gas bubbles that evolve from platinum electrodes. Oxygen and hydrogen bubbles respectively evolve from the surface of the anode and cathode and behave differently in the presence of a magnetic field due to their paramagnetic and diamagnetic characteristics. A magnetic field perpendicular to the surface of the horizontal electrode causes the bubbles to revolve. Oxygen and hydrogen bubbles revolve in opposite directions to create a swirling flow and spread the bubbles between the electrodes, which increases conductivity and the effectiveness of electrolysis. For vertical electrodes under the influence of a parallel magnetic field, a horizontal Lorentz force effectively detaches the bubbles and increases the conductivity and the effectiveness of electrolysis. However, if the layout of the electrodes and magnetic field results in upward or downward Lorentz forces that counter the buoyancy force, a sluggish flow in the duct inhibits the movement of the bubbles and decreases the conductivity and the charging performance. The results in this study determine the optimal layout for an electrode and a magnetic field to increase the conductivity and the effectiveness of water electrolysis, which is applicable to various fields including energy conversion, biotechnology, and magnetohydrodynamic thruster used in seawater.

The Magnetic Anisotropy of Stretched Rubber as a Function of the Tension to Which It Is Subjected

1945 ◽  
Vol 18 (1) ◽  
pp. 8-9 ◽  
Author(s):  
Eugénie Cotton-Feytis
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Uniaxial Crystal ◽  
Horizontal Magnetic Field ◽  
First Approximation ◽  
The Difference ◽  
The Times ◽  
Angular Displacements ◽  
The Magnetic Field ◽  
Oscillation Method

Abstract From the standpoint of its magnetic anisotropy, stretched rubber is comparable in a first approximation to a uniaxial crystal, in which the direction of the axis is the same as the direction of elongation. It is possible to measure this anisotropy by means of the oscillation method used by Krishnan, Guha and Banerjee in studying crystals. The sample to be examined is suspended in a uniform horizontal magnetic field in such a manner that its axis is horizontal. It is then so arranged that the torsion of the suspension wire is zero when the rubber sample is in a position of equilibrium in the field. The times of oscillation T′ and T for very small angular displacements around this position, in the presence and then in the absence of the magnetic field, are then recorded. In this way the difference between the specific susceptibilities in the direction of the axis and in the horizontal direction perpendicular to the axis is calculated by application of the equation:

scholarly journals Simulation study of the plasma-brake effect

2014 ◽  
Vol 32 (10) ◽  
pp. 1207-1216 ◽  
Author(s):  
P. Janhunen
Keyword(s):  
Magnetic Field ◽  
High Performance ◽  
Ionospheric Plasma ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Breaking Force ◽  
Field Orientation ◽  
Particle In Cell ◽  
Leo Satellite ◽  
The Magnetic Field

Abstract. Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent) when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO) satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

Static magnetic fields in vacuum

2018 ◽  
Author(s):  
J. Pierrus
Keyword(s):  
Magnetic Field ◽  
Problem Solving ◽  
Magnetic Fields ◽  
Vector Potential ◽  
Scalar Potential ◽  
Multipole Expansion ◽  
Magnetic Vector Potential ◽  
Magnetic Dipoles ◽  
Static Magnetic Fields ◽  
The Magnetic Field

Wherever possible, an attempt has been made to structure this chapter along similar lines to Chapter 2 (its electrostatic counterpart). Maxwell’s magnetostatic equations are derived from Ampere’s experimental law of force. These results, along with the Biot–Savart law, are then used to determine the magnetic field B arising from various stationary current distributions. The magnetic vector potential A emerges naturally during our discussion, and it features prominently in questions throughout the remainder of this book. Also mentioned is the magnetic scalar potential. Although of lesser theoretical significance than the vector potential, the magnetic scalar potential can sometimes be an effective problem-solving device. Some examples of this are provided. This chapter concludes by making a multipole expansion of A and introducing the magnetic multipole moments of a bounded distribution of stationary currents. Several applications involving magnetic dipoles and magnetic quadrupoles are given.

scholarly journals Magnetic clouds' structure in the magnetosheath as observed by Cluster and Geotail: four case studies

2014 ◽  
Vol 32 (10) ◽  
pp. 1247-1261 ◽  
Author(s):  
L. Turc ◽  
D. Fontaine ◽  
P. Savoini ◽  
E. K. J. Kilpua
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Fields ◽  
Bow Shock ◽  
Field Direction ◽  
Magnetic Clouds ◽  
Magnetic Field Direction ◽  
Field Orientation ◽  
The Impact ◽  
The Magnetic Field

Abstract. Magnetic clouds (MCs) are large-scale magnetic flux ropes ejected from the Sun into the interplanetary space. They play a central role in solar–terrestrial relations as they can efficiently drive magnetic activity in the near-Earth environment. Their impact on the Earth's magnetosphere is often attributed to the presence of southward magnetic fields inside the MC, as observed in the upstream solar wind. However, when they arrive in the vicinity of the Earth, MCs first encounter the bow shock, which is expected to modify their properties, including their magnetic field strength and direction. If these changes are significant, they can in turn affect the interaction of the MC with the magnetosphere. In this paper, we use data from the Cluster and Geotail spacecraft inside the magnetosheath and from the Advanced Composition Explorer (ACE) upstream of the Earth's environment to investigate the impact of the bow shock's crossing on the magnetic structure of MCs. Through four example MCs, we show that the evolution of the MC's structure from the solar wind to the magnetosheath differs largely from one event to another. The smooth rotation of the MC can either be preserved inside the magnetosheath, be modified, i.e. the magnetic field still rotates slowly but at different angles, or even disappear. The alteration of the magnetic field orientation across the bow shock can vary with time during the MC's passage and with the location inside the magnetosheath. We examine the conditions encountered at the bow shock from direct observations, when Cluster or Geotail cross it, or indirectly by applying a magnetosheath model. We obtain a good agreement between the observed and modelled magnetic field direction and shock configuration, which varies from quasi-perpendicular to quasi-parallel in our study. We find that the variations in the angle between the magnetic fields in the solar wind and in the magnetosheath are anti-correlated with the variations in the shock obliquity. When the shock is in a quasi-parallel regime, the magnetic field direction varies significantly from the solar wind to the magnetosheath. In such cases, the magnetic field reaching the magnetopause cannot be approximated by the upstream magnetic field. Therefore, it is important to take into account the conditions at the bow shock when estimating the impact of an MC with the Earth's environment because these conditions are crucial in determining the magnetosheath magnetic field, which then interacts with the magnetosphere.

On the absence of plasma wave emissions and the magnetic field orientation in the distant magnetosheath

1994 ◽  
Vol 21 (24) ◽  
pp. 2761-2764 ◽  
Author(s):  
F. V. Coroniti ◽  
E. W. Greenstadt ◽  
S. L. Moses ◽  
B. T. Tsurutani ◽  
E. J. Smith
Keyword(s):  
Magnetic Field ◽  
Plasma Wave ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
The Magnetic Field

scholarly journals The Magnetic Field of the Crab as Revealed by New, High Resolution, Multi-Band Radio Images

1990 ◽  
Vol 140 ◽  
pp. 79-80
Author(s):  
M. F. Bietenholz ◽  
P. P. Kronberg
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Crab Nebula ◽  
Radio Observations ◽  
Field Orientation ◽  
Magnetic Field Orientation ◽  
The Crab Nebula ◽  
The Magnetic Field ◽  
Made In ◽  
Multi Band

We present and describe recent radio observations of the Crab Nebula, which allow us to determine the magnetic field orientation and depolarization at unprecedented resolution. The observations were made in 1987-1988 using all four configurations of the VLA, at 1410,1515,4625, and 4885 MHz. The resulting maps were all convolved with a clean beam of 1.8″ × 2.0″, elongated in P.A. 80°, and the residuals added back in.

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